A reactive system is one that is in continual interaction with its environment and executes at a pace determined by that environment. Examples of reactive systems are network protocols, air-traffic control systems, industrial-process control systems etc. Reactive systems are ubiquitous and represent an important class of systems. Due to their complex nature, such systems are extremely difficult to specify and implement. Many reactive systems are employed in highly-critical applications, making it crucial that one considers issues such as reliability and safety while designing such systems....